Natural Resources (Conservation) - Background Information
Energy sources exist in two categories. Nonrenewable energy sources include fossil fuels (oil, natural gas, coal), geothermal energy, and nuclear energy. Renewable or perpetual energy resources include conservation, sun, wind, water, and biomass.
Many information sources exist for energy resources and their conservation. Issues related to nonrenewable energy sources include the supply that exists, the rate that it is being used, the economic and political cost of extraction and import/export, the economic and environmental risks of resource extraction, and the ultimate impact of resource use. For instance, acid rain is a by-product of burning some types of coal. Acid rain can have a injurious effect on plants, animals, and human- made structures. Other energy sources, such as nuclear reactors, produce high- level radioactive wastes that are dangerous to handle and store.
Renewable and perpetual resources remove some of the issues raised by nonrenewable energy sources, but bring with them their own issues. The primary advantage of renewable and perpetual resources is that, with wise use, they will always be available. Solar energy is one of the most efficient, low cost, and low impact sources of heat for small spaces, such as homes. Wind energy can be converted into electricity by wind turbines and used efficiently in local areas. Disadvantages have to do mainly with cost. Most renewable and perpetual resources are not available on a consistent and predictable basis; the sun does not always shine, the wind does not always blow. Other issues revolve around the difficulty of efficiently capturing some of these resources. Tapping the energy produced by the tides is difficult due to limited suitable sites and high cost. Trapping solar energy in ocean or in-land ponds is technologically difficult and also has high costs associated with it. Using biomass, such as wood products, is an efficient and cost effective way to create electricity and heat homes. However, without adequate air pollution controls, burning wood products to heat homes creates unacceptable levels of indoor and outdoor air pollution.
The cheapest and easiest way to make more energy available and to reduce the environmental impact of present use is to reduce or eliminate unnecessary energy waste in industry, transportation, and commercial and residential buildings. This can be done by changing our energy-wasting habits, increasing energy efficiency by using the same amount of energy to do less work, and developing new devices that waste less energy than existing ones.
The matter that exists on earth is finite. The carbon atom you exhale as carbon dioxide may change many times, but it is not destroyed. For instance, carbon dioxide may be absorbed by a plant, turned into sugar through photosynthesis, and then eaten by a deer and turned into muscle mass. Later this carbon will be returned to the earth as decomposed organic material in soil, or humus, starting the process once again. Just as the matter on earth cannot be destroyed, neither can it be created. All the material that is available to us on the earth exists here now. Natural resources are defined as all the things we use in our physical environment to meet our needs and wants. This can include the materials used in making clothing, food, vehicles for transportation, and water, land, and space.
There are three categories of natural resources. Renewable resources are those that can be replenished through natural and/or human processes. For instance, trees can be harvested and can grow back to harvestable size in 60 to 200 years. Livestock and vegetables are renewable, since we can replace those used for food sources. Note that even though these resources can be replaced, they cannot be replaced immediately. If we eat all the tomatoes from our garden in August, we will have no more (at least from our garden) until the next summer. If we removed all the trees today, no wood products would be available for 60 years. The management practice that allows the harvest of renewable resources at the same rate that they can be replaced is called sustainable yield.
Nonrenewable resources are those resources that exist in fixed amounts. The process of creating non-renewable resources takes millions of years. Once these resources are used up, there is no natural process that exists to replace them. Fossil fuels, such as oil, coal, and natural gas are obvious examples of natural resources. Fossil fuels were formed from plant and animal life that existed millions of years ago. Large layers of these organic materials were covered under rock and water and underwent chemical changes caused by extreme heat and pressure. There is no reasonable method of creating a sustained yield of these products unless we didn't use them at all. Metals, such as aluminum, copper, silver and gold, and minerals, such as phosphates, sulfur, sand and diamonds, are also considered nonrenewable resources.
Perpetual resources are those that seem to be endless human time frames. These resources include heat energy from the sun and mechanical energy from the winds and tides. Note that these resources are all forms of energy. Different than matter, energy comes into the earth system with every sunrise, is changed many times, and then escapes back into space as heat. Since the sun is the ultimate source of almost all the energy forms that we can think of, these sources of energy will exist as long as the sun. The sun is predicted to last another 4 billion years.
The most commonly thought of natural resources are metals and nonmetals, energy sources, water, land, food, wild plants and animals, and soils.Technology has both helped us solve some of our resource problems and, simultaneously, has complicated other solutions or caused problems of its own. Through the use of technology, we have been able to extract resources previously out of our reach, grow more crops than previously possible, and obtain sources of energy that were only explored in science fiction novels. But technology has also increased the rate of resource use and increased threats from pollution. The following sections will briefly describe each of these resources, indicate other parts of the science core curriculum that deal with similar topics, and describe the role of technology in each resource.
Soil and soil conservation is an important part of the fourth grade curriculum and can be built upon as part of this unit. Fundamental understandings about soil include its composition (soil horizons) and formation (through weathering). Soil, especially topsoil, is classified as a renewable resource. The replacement of 1 inch of topsoil takes 200 to 1000 years, depending on climate and soil type. Soil erosion, or the movement of soil from one place to another, occurs when the natural soil surface is disturbed. Construction and agriculture are two of the leading causes of soil erosion. The two main forces causing soil erosion are wind and flowing water. Soil conservation involves various methods to reduce soil erosion, to prevent depletion of soil nutrients, and to restore nutrients already lost by leaching, erosion, and excessive crop harvesting. Conservation techniques include better farming practices such as terracing, contour farming, and strip cropping. Windbreaks can also reduce wind erosion. Maintaining a ground cover on exposed soils will reduce erosion and increase water penetration. Fertilizers, both manufactured and natural, can maintain soil nutrient levels. Unfortunately, the production of manufactured fertilizers depletes our nonrenewable resource, phosphorous, and can cause air and water pollution.
Water is covered extensively in Standard 3 of the fifth grade curriculum. Information related to water supply, renewal, uses, resource problems, and resource management, along with the properties of water, are covered in the background section of that standard.
Agriculture uses more of the earth's land, water, soil, plant, animal, and energy resources and causes more pollution and environmental degradation than any other human activity. With the world's population growing at 247,000 people per day, our ability to produce enough high quality food to feed everyone will be tested. Although about 80,000 species of plants are edible, only about 30 crops feed the world. Four crops - wheat, rice, corn and potato - make up more of the world's total food production than all others combined.The rest of the world's diet consists mainly of fish, meat, milk, eggs, and cheese.
Plants convert a large portion of the energy they receive from the sun into plant material. Despite this high conversion rate, some of the energy absorbed from the sun is used by the plant in order to grow and carry out other life functions. This loss of energy is increased as one moves up higher on the food chain. The cow that eats the grass stores only 10% of the energy that it gains from its food. The rest of the energy is used to support cow growth and life functions. Since energy from plants is lost as it is converted into animal products, eating "higher on the food chain" is done at a high energy cost. That is, less than 1% of the energy received directly from the sun by the plants is available to a consumer of a first- level consumer--in this case, the consumer of a cow. Eating "lower on the food chain" means more energy mass!
Food must not only be plentiful, it must also be nutritious. The proper amount of protein, carbohydrates, fats, vitamins, and minerals must be contained in a diet in order to ensure a healthy body. Problems associated with improper nutrition include undernutrition, malnutrition, decreased disease resistance, decreased energy, decreased ability to learn, decreased ability to work, increased death rate for children, and a shortened life expectancy. Each year 20-40 million people - half of them under age 5 - die from problems created by improper nutrition.
Technology is often heralded as the solution to a limited world food supply. In some respects, the hope is appropriate. Scientists were able to significantly increase the world food supply in two green revolutions in the 50s and 60s. New hybrid crop varieties were created that were more resistant to disease, produced higher yields, and could grow on decreased water supplies. Unfortunately, such crops often required higher use of fertilizers and pesticides - products that many countries cannot afford. Green revolutions are also limited by the amount of land available for agriculture. Other problems associated with the green revolution include the loss of genetic diversity, overuse of water for agriculture, and displacement of protein-rich legumes (such as peas and beans) by low-protein crops (such as potatoes and wheat). Other solutions to world food supply are being sought in the oceans. Many experts believe that we can significantly increase the fish and shellfish harvest by increased fishing efforts, increased fish farming, and decreased waste. Other analysts disagree, pointing to over-fishing and the pollution of estuaries.
Four important types of land resources are forests, rangelands, parks, and wilderness areas. These areas are coming under increasing stress as the population and economic development grows. Protecting and managing these areas so that they can be used on a sustainable basis will be an important challenge now and in the future.
A potentially renewable resource, 34% of the earth's surface is covered by forests. Forests supply us with lumber, paper pulp, medicines, and many other products. World-wide, about one-half of the timber cut each year is used for heating and cooking. One-third is converted to lumber products. One-sixth is converted to pulp and used in paper products.
In addition to lumber, forests play an important ecological function. Acting as great sponges, forest watersheds hold and regulate the flow of water from the mountains. Forests also convert carbon dioxide into oxygen in the process of photosynthesis. Removal of large tracts of forest contributes to increased levels of carbon dioxide and contributes to global warming (the greenhouse effect). Forests also provide habitats for large numbers of plants and animals.
Deforestation occurs when forests are removed, typically for agricultural uses or to build homes. The most dramatic loss of the biome is occurring in the tropical rain forests of the world. About 55% of the world's original area of tropical forests have been cleared for timber, cattle grazing, fuelwood, and farming. If clearing and degradation continue at the current rate, almost all tropical forests will be gone or severely damaged in the next 30 years. Ecologists warn that the degradation and loss of these extremely diverse biomes could cause the premature extinction of 1 million plant and animal species by the beginning of the next century. This loss is tremendous when one considers the medical, economic, and ethical implications of such an action.
Forests are threatened most by overharvesting. In many steep areas, clearcutting (the removal of all trees from an area) is the most economic method of tree removal. Unfortunately, this technique also exposes very fragile areas to erosion. Selective cutting, or the removal of only those trees that are of harvestable age, is an expensive alternative to clearcutting. Removal of old-growth forests are also of concern. Old-growth forests are virgin forests containing massive trees that are hundreds, sometimes thousands, of years old. Examples include western forests of Douglas fir, western hemlock, giant sequoia, and coastal redwoods. Generally, old- growth forests have a greater diversity of plant and animal life than secondary (second growth) forests.
Forest fires are also a threat to forest management. There are two types of fires. Surface fires usually only burn the undergrowth and leaf litter in the forest and do not hurt mature trees. Surface fires help maintain the forest by releasing minerals and nutrients stored in the forest litter. Many animal species also benefit from surface fires, since young sprouts growing after the fire are more nutritious than older plants. Many plants also depend on fires. Some pine cones will not open to release their seeds unless they are heated by a fire. Crown fires are extremely hot fires that burn ground vegetation and tree tops. They usually occur in forests where fire has been prevented for several decades, allowing for the buildup of dead wood, leaves, and ground litter. Crown fires destroy all plants and animals in their path and increase soil erosion. The protection of forest lands from fire has come under debate. Forest managers see the benefit of surface fires in forest areas. When these fires turn into crown fires, however, public outcry is often heard, and management practices are questioned. A recent example of this occurred with the fires in Yellowstone National Park in 1988.
About 42% of all U.S. land is public land: national
parks, forests, wildlife refuges, and lands administered by the Bureau of Land Management
(BLM).Of this, 22% of the land is in the western states, and 73% is in Alaska.
Federally administered lands contain a large portion of the country's timber, grazing
land, and energy and mineral resources. Many of these lands (national forests, grasslands,
and BLM lands) are managed under the philosophy of multiple use.This
philosophy states that land, if used wisely, can sustain a number of activities and
therefore benefit a number of audiences. The land is used for timbering, grazing,
agriculture, mining, oil and gas leasing, recreation, sport hunting, sport and commercial
fishing, and conservation of watershed, soil, and wildlife resources. National parks and
wilderness areas are restricted-use lands.The management goals of the national
parks are to preserve scenic and unique natural landscapes, preserve and
interpret the country's historic and cultural heritage, provide protected wildlife
habitats, protect wilderness areas within the parks, and provide certain types of
recreation. Wilderness areas include 474 roadless areas within the
national parks, national wildlife refuges, and national forests. These areas are to be
preserved in essentially untouched condition "for the use and enjoyment of the
American people in such a manner as will leave them unimpaired for future use and
enjoyment as wilderness." Wilderness areas are open for hiking, sport fishing,
camping, non- motorized boating, and, in some areas, sport hunting and horseback riding.
Roads, timber harvesting, grazing, mining, commercial activities, and human-made
structures are prohibited, except where such activities occurred before the area's
designation as wilderness.
Rangeland makes up almost half of the earth's ice-free land. Rangelands are grasslands in semiarid areas too dry for rain-fed crops. Only about 42% of the world's rangeland is used for grazing livestock. Much of the rest is too dry, cold, or remote. Most of the grasses on rangelands have deep, complex root systems. These roots help prevent soil erosion and efficiently collect the low levels of precipitation that fall. Browsing animals eat the tips of these grasses. Since grasses grow from the base of their shoots rather than from their tips (like trees), they grow back after browsing. Overgrazing is a threat to many rangelands. Overgrazing occurs when too many animals feed for too long in a particular area. Overgrazed areas are converted from continuous grasslands to patches of grass. This change makes the soil more vulnerable to erosion, especially by the wind. The invasion of prickly pear and woody shrubs is often an indication of overgrazing.
Today there are over 1000 national parks in over 120 countries around the world. This has been an important achievement in the global conservation movement. Forty-nine of those parks are found in the U.S., mostly in the west. The major threat to parks involves people. In many ways, we are "loving our parks to death." As more people learn to appreciate the beauty and recreational value of our park systems, traffic, road, and accommodation needs are increased. These increases are often in direct conflict with the desire to maintain the beauty and rustic nature of our parks. Other threats to the health of our parks include development outside of the park boundaries. Mines, ranching, recreational areas, and dams often threaten the natural resources found within the park boundaries. Animals know no boundaries and cross over onto public and private lands. Pollution, noise, and increased threat of global warming cannot be stopped at park entrances. Multiple strategies are being discussed to save the national parks, including limiting entrance to parks during busy seasons and protecting the greater park ecosystem. Discussion and implementation of these measures will create controversy from park enthusiasts and local populations.
Wilderness areas provide wild places where one can experience natural beauty and solitude. Wilderness areas also protect intact natural biomes from undue interference from human activity. Since 1900, conservationists have been fighting a largely loosing battle to protect undeveloped tracts of land in the United States by making them part of the National Wilderness Preservation System. Only 3.9% of U.S. lands (1.8% in the lower 48 states) are presently protected in the system. About 0.2% of the total length of U.S. rivers have been protected from development as part of the Wild and Scenic River Systems. Utah has recently been engaged in a debate over state wilderness designation. Of over 16 million acres studied for wilderness designation, wilderness proponents supported the designation of 5.6 million acres as wilderness. After meeting with locals, environmentalists, and representatives of timber, ranching, mining and energy resources, the state government countered with a request for 1.7 million acres. The debate continues today.